Would you be terribly upset if I aped your technique to make my own assets that are visually compatible with this one? Its aesthetic is perfect, but the scope is a bit too narrow for some of the kinds of projects I wish to make.
I couldn't make an asset pack that would work for every project, so I fully expect game devs to supplement the pack with custom art. So long as it's not fed to an AI model for more asset generation--that is is against the license.